Lock-off device for electric switches



Jan. 13, 1953 p BALLQU 2,625,617

LOCK-OFF DEVICE FOR ELECTRIC SWITCHES Filed Aug. 17, 1949 INVENTOR. /?/CHA/?D P. BALL 00 F! T TORNEYS Patented Jan. 13, 1953 LOCK-OFF DEVICE FOR ELECTRIC SWITCHES.

Richard P. Ballou, Hartford, Comn, assignor to Federal Electric Products Company, Newark,

N. J., a corporation Application August 17, 1949, Serial No. 110,731 4 Claims. (01. 200-42) This invention relates generally to push button or other manually operated switches and more particularly to a lock-off device for such switches, especially of the type used to control electric motors, magnetically operated contactors, etc.

A locking bar, comm-only referred to as a lockoff, is generally used with the stop button of a control switch to retain the latter in de ressed, or circuit-open, condition. In properly wired circuits provided with a plurality of control switches located at various points thereof, the normally closed stop-switches at the various control stations are connected in series circuit relation whereby the depression of any one stop-switch button will open or de-energiZe the circuit. In such circuits, the normally open start switches at the various control stations are so connected in the circuit that the circuit can be closed by closing the start switch at any station. There are circumstances under which it may be desirable to prevent the operation of equipment from a remote station while permitting said operation only from a switch located near or at the equipment, for example, for setting-up or adjusting the equipment. This can be accomplished by locking the start button of the start switch at the remote station to prevent the closing of said switch. Therefore, it is an object of this invention to provide a lock-off device that is adapted to be used either for looking a stop-switch open, whereby to retain a circuit in open or de-energized condition by retaining one of its stop buttons in circuit-open position or to lock a start switch open so that the closing or energizing of a circuit can be accomplished only from a predetermined station by locking the start buttons at all other stations against operation.

Another object of this invention is to provide a lock-off device that is adapted to retain the push-button or other manually operated part of a switch in depressed condition, or to prevent the depression thereof.

A further object of this invention is to provide a lock-off device especially adapted for use with switch enclosures having lever or cam operated push-buttons within the enclosure, for example, as in weatherproof and explosion resisting enclosures.

A further object of this invention is to provide an improved lock-off device that comprises a minimum of simply fabricated parts that can be easily added to the control switch without requiring any special machining thereof.

A further object of this invention is to provide a lock-off device having means to retain said device in operativ position against vibration and the force of gravity. r

The above and other objects, features and advantages of the invention will be fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

Fig. 1 is a plan view of a switch enclosure embodying the invention;

Fig. 2 is a side view of the switch enclosure;

. Fig. 3 is a sectional view taken along the line 3-3 of Fig. 1;

Fig. 4 illustrates, on an enlarged scale, the retaining member of the lock-off device;

Fig. 5 is a fragmentary plan view illustrating the relative disposition of the retaining member and the switch actuating member, the latter being retained in depressed position;

Fig. 6 is a sectional view taken along the line 6-45 of Fig. 5;

Fig. 7 is a view similar to Fig. 5 showing the retaining member positioned to prevent the de-- pression of the switch actuating member;

Fig. 8 is a sectional view taken along the line 8-8 of Fig. 7

Fig. 9 illustrates, on an enlarged scale, a modified retaining member and Fig. 10 illustrates, on an enlarged scale, a modified retainer plate of the lock-oil device.

Referring to the drawings, there is illustrated a control switch enclosure ill, of the known weatherproof or explosion resisting type, comprising the cover portion l2 and the body portion l4, both preferably cast from a suitable material and provided with the threaded holes 16 for the fastening screws l8 to secure the cover to the container. A push-button or contact operating member 20 is mounted, internally of enclosure ID, on a contact actuating stem 22 which is adapted to cause the engagement or the disengagement, as the case may be, of a pair of electrical contacts of the push-button switch generally indicated by the box 24, as is well known. The pushbutton 20 is depressed against the bias of a compression spring 26 disposed about stem 22, one end of the spring bearing against the push-button and the other end of the spring bearing against the switch casing. It will be understood that switch 24 may be a normally open switch, such as a start switch for example, or a normally closed switch, such as a stop switch and that spring 26 normally holds the operating stem in its projected position so that inward movement of said stem against the pressure of said spring is necessary to close the switch, in the case of a start switch, and to open the switch, in the case of a stop switch. Push-button switches of this type are well known and therefore require no further description. To operate the push-button 20 from a point externally of cover 12, there is provided the preferably cylindrical member or spindle 23 which is mounted for rotation in the aperture 39 in wall 32 of cover [2, one end 34 of said member extending into the cover and the opposite end 36 projecting therefrom. Spindle 28 is provided with collars 3! to prevent axial movement thereof in Wall 32. A cam or lever arm 38 is secured to end 34 and engages push-button 2B whereby, upon the clockwise rotation of member 28 resulting from the depression of the operating part or finger piece 66, which is fixed to end 36, the cam depresses the push-button against the upward bias of spring 26.

The lock-01f unit 42 comprises a retainer plate .44 provided with aligned slot means 46 and 18, each constituted by a longitudinal slot 56 and a transverse slot 52 at one end thereof, as illustrated in Fig. 2, the upper end of slot is opening into the transverse portion of slot 56 to provide one continuous slot. A retainer member or slider 54 is slidably mounted in slots 46 and 48. 'Retainer member 54 is provided at each end thereof with a narrow neck 56 adapted to slidably engage slot 56, with an ear or guide part 53 extending from said neck and adapted to be inserted in the transverse slot 52, and with a portion 55 extending between the necks thereof. Retainer member 154 is mounted in plate is from the rear thereof,

by inserti g parts 56 in the cooperating transverse slots 52 whereby the necks 56 can ride longitudinally of slots b, with parts '68 projecting from the frontof plate 44 for guiding said member in the slots and portion 55 extending rearwardly of the plate. Plate 44 is mounted, by screws 60, on

ribs 62 and 64 extending from cover I 2 and forming ahousing thereon which is open at theside on which the plate is mounted. 'It will'be noted from Fig.2, that with the plate somounted, the transverse portion 52 of slot 48 is below the upper surface of rib 62 and the lower ear 58 is positioned above said surface whereby slider 54'is retained against disengagement from plate -42. In the neutral or retractedposition of the slider 54,

as illustrated in Figs. 1 and2, actuating part 66 may be-f-reely depressed due to the clearance be tween said part and slider portion 55.

A modified form of theretainer member 54 is illustrated in Fig. 9, wherein a retainer member is provided with a stem #0 which extends'from portion 55' and engages slot 51 said stem being dimensioned-to provide-an adequate bearingsurface in the slot to prevent rotation of the slider. A guide part i2 is carried by the stem, said part being insertable in slot portion 52 from the rear of plate- .2 and projecting from the front thereof to retain the stem against removal from slot 56.

.Stem i6 is oif-set from the centerof portion 55' so additional screw-holes therein. It is apparent that plate 42' may be mounted in the same position as plate 42, as illustrated in Fig. 2, by removing the two screws I8, illustrated in said figure, and securing the bent portions 18 to cover portion I 2 by said screws.

While retainer plates 42 and 42 have been illustrated as having slotted portions 46 and 48 which merge into one continuous slot, it is apparent that a plate having two separate slots may be used with either retaining member 54 or 54'. It will also be apparent that a plate having more than two separate slots may be used with a retainer member having more than two engaging portions56.

Assuming that push-button 20 is the STOP buttonof one Of a plurality of serially connected STOP button switches and it is desired to completely de-energize the circuit so as to prevent the operation of equipment in the circuit from any station, actuating part 40 is depressed, thereby depressing push-button 2,0 to open the circuit, and slider 54 is moved from its neutral position, by part 55, upwardly along slots 46 and 48, respectively, to the position illustrated in Figs. 5 and 6, wherein slider portion 55 is disposed above actuating part 56 to retain it in depressed position thereby retaining button 20 in depressed or circuit-open condition and preventing the energization of the circuitfroman control-switch thereof.

Assuming that push-button 2 0 is the button of a START switch at one station and it is desired to prevent the operation of equipment in a circuit by said switch, but to permit its operation by a switch at another station, the slider 54 of the switch at the first mentioned station is moved from its neutral position, by movingpart 55, upwardly along slots 46 and 48, respectively, to the locking position illustrated in Figs. '7 and 8, wherein slider portion 55 is disposed below the actuating part 46 to prevent the depression thereof. It is apparent that inadvertent operation of the equipment from the firststationis effectively prevented.

It will be noted that the locked-off device may be used either with a normally open switch, ordinarily a start switch, or with anormally closed switch, ordinarily a stop switch. Whena circuit is provided with a plurality of start and stop switches, any one or all such switches can be locked either closed or open, as may be desired. Forexample if it is desired toplace the control of the circuit exclusively at one station, all of the start switches and stop switchesexcept the start and stop switch at said one-station can be locked in their normally open and closed conditions, respectively. On the other hand, the locking of any stop switch, at any station, in its open condition serves to prevent the energizaticn of the circuit irrespective of the operation of astart switch at any of the stations.

To prevent thereturnof the slider54 from its operative or locking position-to its neutral position, a padlock can beplaced between the slider and plate E2 to keep slider portion55 from disengaging part it and moving back to its neutral position. For this purpose, plate 42 is provided with the cut-out portions 66, illustrated in Fig. 2, to receive the padlock. If no padlock is used,,and the slider is positioned .above the actuating part 46, as in Figs. 5 and 16, the slider can be retained in said position by providing an offset po tio '6 at th o van to th lef ofqslot Th :upwar bia a plied by sem resa n spring 26 to push-button 20 will tension actuating part 45 in a counter-clockwise direction to slightly lift slider 54 so that the upper neck portion 56 will engage off-set 68 thereby preventing the return of the slider to its neutral position as a result of gravitation or vibration.

Although the invention has been described with reference to switches mounted in a casing or housing referred to as one which may be weatherproof and/or shock-resistant, it will be appreciated that the invention may be applied to switches disposed in other types of casings or enclosures or otherwise mounted.

While my invention has been illustrated and described in connection with a switch-actuating part and shaft having a rotary motion, it will be understood that its application is not limited thereto and that my invention is applicable as well with actuating part-s having other types of motion, for example, an by way of illustration only, to an actuating part and shaft having a rectilinear motion.

While I have shown and described the presently pre erred embodiment of mv invention, it will be understood that various changes in the details of construction and in the form and arran ement of parts may be made without de arting from the underlying idea or principles of this invention within the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is:

1. In a sw tch havin a weather p oof and explosion resisting enclosure, the combination with enclosure of a movable actuatin member having a port on within said enclosure for operating said switch and a portion extending outwardly of said enclosure for operating said member, and lock-off means for said actuating member comprising a plate mounted exteriorly of said enclosure and spaced laterally outwardly from said latter portion, and a lock-off member slidably mounted on said plate and extending into the path of movement of said latter portion, said lock-on" member being movable from a neutral position on said plate, clear of the path of movement of said latter portion, to an operative position in engagement with said latter portion to prevent the movement of said actuating member, said enclosure being provided on the outer surface thereof with spaced laterally extending ribs and said latter portion being disposed between confronting rib surfaces, said plate extending transversely of said ribs and said lock-off member being disposed for movement between said confronting surfaces.

2. In a switch having a weather proof and explosion resisting enclosure, the combination with said enclosure of a movable actuating member having a portion within said enclosure for operating said switch and a portion extending outwardly of said enclosure for operating said member, and lock-off means for said actuating member comprising a plate mounted exteriorly of said enclosure and spaced laterally outwardly from said latter portion, and a lock-oiT member slidably mounted on said plate and extending into the path of movement of said latter portion, said lock-off member being movable from a neutral position on said plate, clear of the path of movement of said latter portion, to an operative position in engagement with said latter portion to prevent the movement of said actuating member, said enclosure being provided on the outer surface thereof with spaced laterally extending ribs and said latter portion being disposed between confronting rib surfaces, said plate extending transversely of said ribs and said lock-off member being disposed for movement between said confronting surfaces, said enclosure having a body portion in which said switch is contained and a cover portion therefor, said ribs being provided on said cover portion and said actuating member extending through said cover portion.

3. In a switch having a weather proof and explosion resisting enclosure, the combination with said enclosure of a movable actuating member having a portion within said enclosure for operating said switch and a portion extending outwardly of said enclosure for operating said member and lock-off means for said actuating member comprising a plate mounted exteriorly of said enclosure and spaced laterally outwardly from said latter portion, and a lock-off member slidably mounted on said plate axially of the latter, said lock-on member extending into the path of movement of said latter portion and movable from a neutral position on said plate, clear of the path of movement of said latter portion, to an operative position in engagement with said latter portion to prevent the movement of said actuating member.

4. In a switch having a weather proof and explosion resisting enclosure, the combination with said enclosure of a movable elongated actuating member having a portion within said enclosure for operating said switch and a portion extending outwardly of said enclosure for operating said member, said enclosure having a housing formed thereon which is open at least at one side there of, said latter portion being disposed in said housing and extending toward said side thereof, and lock-off means for said actuating member comprising a plate mounted at said housing side and disposed transversely of the axis of said member and a lock-01f member slidably mounted on said plate along an axis substantially parallel to the longitudinal axis of said plate, said lockoff member having a part extending into said housing and into the path of movement of said latter portion, said part being movable from a neutral position on said plate clear of the path of movement of said latter portion, to an operative position in engagement with said latter portion to prevent the movement of said actuating member.

RICHARD P. BALLOU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 613,955 Alter et a1 Nov. 8, 1898 1,676,971 Weaver July 10, 1928 1,875,225 Despard Aug. 30, 1932 2,107,056 Kistner Feb. 1, 1938 2,169,860 Von Hoorn Aug. 15, 1939 2,290,516 Willmann July 21, 1942 2,336,425 Shenton Dec. 7, 1943 

